Ophthalmic solution

ABSTRACT

The present invention relates to an ophthalmic solution comprising a prostaglandin compound and viscosity-increasing compound. The ophthalmic solution of the invention is excellent in stability and can provide long lasting and increased effect when administrated topically to the eyes of a patient.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 14/048,250filed Oct. 8, 2013, which is a continuation of application Ser. No.11/110,698 filed Apr. 21, 2005, now U.S. Pat. No. 8,580,851 issued Nov.12, 2013, which is a continuation-in-part application of applicationSer. No. 10/644,870 filed on Aug. 21, 2003 claiming the benefit under 35U.S.C. 119(e) of U.S. Provisional Application No. 60/404,779 filed onAug. 21, 2002 and International Patent Application No. PCT/JP2004/003288filed on Mar. 12, 2004, designating U.S.

FIELD OF THE INVENTION

The present invention relates to an ophthalmic solution or an eye dropcomposition comprising a prostaglandin compound and aviscosity-increasing compound.

The present invention also relates to a method for treating glaucomaand/or ocular hypertension.

BACKGROUND ART

Prostaglandins (hereinafter, referred to as PGs) are members of class oforganic carboxylic acids, which are contained in tissues or organs ofhuman and other mammals, and exhibit a wide range of physiologicalactivities. PGs found in nature (primary PGs) have, as a generalstructural property thereof, a prostanoic acid skeleton as shown in theformula (A):

On the other hand, some synthetic analogues have modified skeletons. Theprimary PGs are classified into PGAs, PGBs, PGCs, PGDs, PGEs, PGFs,PGGs, PGHs, PGIs and PGJs on the basis of the structural property of thefive membered ring moiety, and further classified into the followingthree types by the number and position of the unsaturated bond in thecarbon chain moiety.

Type 1 (subscript 1): 13,14-unsaturated-15-OHType 2 (subscript 2): 5,6- and 13,14-diunsaturated-15-OHType 3 (subscript 3): 5,6-, 13,14-, and 17,18-triunsaturated-15-OH.

Further, PGFs are classified on the basis of the configuration of thehydroxyl group at the 9-position into α type (wherein the hydroxyl groupis of the α-configuration) and β type (wherein the hydroxyl group is ofthe β-configuration).

In addition, some 15-keto-PGs (PGs having an oxo group at position 15 inplace of the hydroxy group) and 13,14-dihydro-15-keto-PGs have beenknown as substances naturally produced by enzymatic actions duringmetabolism of the primary PGs. 15-keto-PGs have been disclosed in U.S.Pat. Nos. 5,073,569, 5,534,547, 5,225,439, 5,166,174, 5,428,0625,380,709 5,886,034 6,265,440, 5,106,869, 5,221,763, 5,591,887,5,770,759 and 5,739,161. The contents of these publications are hereinincorporated by reference.

Some prostaglandin compounds have been known to be useful aspharmaceutical agents in the ophthalmic area, namely as an ocularhypotensive agent or an agent for treatment of glaucoma. For example,latanoprost, that is 13,14-dihydro-17-phenyl-18,19,20-trior-PGF_(2α)isopropyl ester, travoprost, that is 16-(3-trifluoromethylphenoxy)-17,18,19,20-tetranor PGF_(2α) isopropyl ester and bimatoprost,that is 17-phenyl-18,19,20-trinor-PGF_(2α) N-ethylamide have alreadybeen placed on the market under the name of Xalatan™, Travatan™ andLumigan™ eye drops for the treatment of glaucoma and ocularhypertension.

Further, 15-keto-prostaglandin compounds have been known to be useful aspharmaceutical agents in the ophthalmic area, namely as an ocularhypotensive agent or an agent for treatment of glaucoma, see U.S. Pat.Nos. 5,001,153; 5,151,444, 5,166,178, 5,194,429 and 5,236,907, fortreatment of cataract, see U.S. Pat. Nos. 5,212,324 and 5,686,487, forincreasing the choroidal blood flow, see U.S. Pat. No. 5,221,690 and fortreatment of optic nerve disorders, see U.S. Pat. No. 5,773,471. Thecontents of these USPs are herein incorporated by reference. Especially,isopropyl ester of 13,14-dihydro-15-keto-20-ethyl-PGF2α has already beenplaced on the market under the name of Rescula™ (common name: isopropylunoprostone) ophthalmic solution for treatment of glaucoma and ocularhypertension. Rescula™ ophthalmic solution provides sufficient ocularhypotensive effect by administrating twice a day.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an ophthalmic solution,which is excellent in stability, potency or duration of the activity.

This inventor found that an ophthalmic solution comprising a PG compoundand a specific viscosity-increasing compound is excellent in stabilityand provides long-lasting and increased effects and therefore, saidophthalmic solution shows great advantages.

Accordingly, the present invention provides an ophthalmic solutioncomprising a prostaglandin compound of formula (I) shown below and atleast one viscosity-increasing compound selected from the groupconsisting of acrylate polymers, polyols, cellulose polymers,polysaccharides and polyl-lactams.

The present invention also provides a method for improving the durationof the effect of an ophthalmic solution comprising a prostaglandincompound of formula (I) shown below when administrated to the eyes of asubject, comprising: adding at least one viscosity-increasing compoundselected from the group consisting of acrylate polymers, polyols,cellulose polymers, polysaccharides and polyl-lactams to the ophthalmicsolution.

The present invention further provides a method for treating ocularhypertension and/or glaucoma, which comprises administrating anophthalmic solution comprising as an active ingredient thereof aprostaglandin compound of formula (I) shown below and at least oneviscosity-increasing compound selected from the group consisting ofacrylate polymers, polyols, cellulose polymers, polysaccharides andpolyl-lactams.

DETAILED DESCRIPTION

The nomenclature of the PG compounds used herein is based on thenumbering system of prostanoic acid represented in the above formula(A).

The formula (A) shows a basic skeleton of the C-20 PG compound, but thepresent invention is not limited to those having the same number ofcarbon atoms. In the formula (A), the numbering of the carbon atomswhich constitute the basic skeleton of the PG compounds starts at thecarboxylic acid (numbered 1), and carbon atoms in the α-chain arenumbered 2 to 7 towards the five-membered ring, those in the ring are 8to 12, and those in the ω-chain are 13 to 20. When the number of carbonatoms is decreased in the α-chain, the number is deleted in the orderstarting from position 2; and when the number of carbon atoms isincreased in the α-chain, compounds are named as substitution compoundshaving respective substituents at position 2 in place of carboxy group(C-1). Similarly, when the number of carbon atoms is decreased in theω-chain, the number is deleted in the order starting from position 20;and when the number of carbon atoms is increased in the ω-chain,compounds are named as substitution compounds having respectivesubstituents at position 20. Stereochemistry of the compounds is thesame as that of the above formula (A) unless otherwise specified.

In general, each of PGD, PGE and PGF represents a PG compound havinghydroxy groups at positions 9 and/or 11, but in the presentspecification they also include those having substituents other than thehydroxyl groups at positions 9 and/or 11. Such compounds are referred toas 9-dehydroxy-9-substituted-PG compounds or11-dehydroxy-11-substituted-PG compounds. A PG compound having hydrogenin place of the hydroxy group is simply named as 9- or 11-dehydroxycompound.

As stated above, the nomenclature of PG compounds is based on theprostanoic acid skeleton. However, in case the compound has a similarpartial construction as a prostaglandin, the abbreviation of “PG” may beused. Thus, a PG compound of which α-chain is extended by two carbonatoms, that is, having 9 carbon atoms in the α-chain is named as2-decarboxy-2-(2-carboxyethyl)-PG compound. Similarly, a PG compoundhaving 11 carbon atoms in the α-chain is named as2-decarboxy-2-(4-carboxybutyl)-PG compound. Further, a PG compound ofwhich ω-chain is extended by two carbon atoms, that is, having 10 carbonatoms in the w-chain is named as 20-ethyl-PG compound. These compounds,however, may also be named according to the IUPAC nomenclatures.

According to the IUPAC naming system, for example,13,14-dihydro-15-keto-16R,S-fluoro-PGE₂ is(Z)-7-((1R,2R,3R)-3-hydroxy-2-[(4R,S)-fluoro-3-oxo-1-octyl]-5-oxocyclopentyl)-hept-5-enoic acid;13,14-dihydro-15-keto-20-ethyl-11-dehydroxy-11R-methyl-PGE₂ methyl esteris methyl7-{(1R,2S,3S)-3-methyl-2-[3-oxo-1-decyl]-5-oxocyclopentyl}-hept-5-enoate;and 13,14-dihydro-6,15-diketo-19-methyl-PGE₂ ethyl ester is ethyl7-{(1R,2S,3S)-3-hydroxy-2-(7-methyl-3-oxo-1-octyl)-5-oxocyclopentyl}-6-oxo-heptanoate.13,14-dihydro-15-keto-20-ethyl-PGF₂α isopropyl ester is isopropyl(Z)-7-[(1R,2R,3R,5S)-3,5-dihydro-2-{3-oxo-1-decyl)-cyclopentyl]-hept-5-enoate;and 13,14-dihydro-15-keto-20-methyl-PGF₂α methyl ester is methyl(Z)-7-[(1R,2R,3R,5S)-3,5-dihydroxy-2-{3-oxo-1-nonyl}-cyclopentyl]-hept-5-enoate.

The 15-keto-PG compound used in the present invention may be anyderivative of a PG insofar as having an oxo group at position 15 inplace of the hydroxy group, and may further include a compound havingone double bond between positions 13 and 14 (15-keto-PG type 1compound), two double bonds between positions 13 and 14, and positions 5and 6 (15-keto-PG type 2 compound), and three double bonds betweenpositions 5 and 6, positions 13 and 14, and positions 17 and18(15-keto-PG type 3 compound), and a derivative thereof wherein thebond between the positions 13 and 14 is single bond, in place of thedouble bond (13,14-dihydro-15-keto-PG compound).

Typical examples of the PG compounds used in the present inventioninclude 15-keto-PG type 1, 15-keto-PG type 2, 15-keto-PG type3,13,14-dihydro-15-keto-PG type 1, 13,14-dihydro-15-keto-PG type2,13,14-dihydro-15-keto-PG type 3 and the derivatives thereof.

Examples of the substitution compounds or derivatives include a PGcompound of which the carboxy group at the end of the alpha chain isesterified; physiologically acceptable salt thereof; an unsaturatedderivative having a double bond between positions 2 and 3 or a triplebond between positions 5 and 6; PG compounds having substituent(s) oncarbon atom(s) at position(s) 3, 5, 6, 16, 17, 18, 19 and/or 20; and PGcompounds having lower alkyl or a hydroxy (lower) alkyl group atposition 9 and/or 11 in place of the hydroxy group.

According to the present invention, preferred substituents on the carbonatom at position(s) 3, 17, 18 and/or 19 include alkyl having 1-4 carbonatoms, especially methyl and ethyl. Preferred substituents on the carbonatom at position 16 include lower alkyl such as methyl and ethyl,hydroxy, halogen atom such as chlorine and fluorine, and aryloxy such astrifluoromethylphenoxy. Preferred substituents on the carbon atom atposition 17 include halogen atom such as chlorine and fluorine.Preferred substituents on the carbon atom at position 20 includesaturated or unsaturated lower alkyl such as C₁₋₄ alkyl, lower alkoxysuch as C₁₋₄ alkoxy, and lower alkoxy alkyl such as C₁₋₄ alkoxy-C₁₋₄alkyl. Preferred substituents on the carbon atom at position 5 includehalogen atoms such as chlorine and fluorine. Preferred substituents onthe carbon atom at position 6 include an oxo group forming a carbonylgroup. Stereochemistry of PGs having hydroxy, lower alkyl orhydroxy(lower)alkyl substituent on the carbon atom at positions 9 and 11may be α, β or a mixture thereof.

Further, the above described derivatives may have a ω chain shorter thanthat of the primary PGs and a substituent such as alkoxy, cyclohexyl,cyclohexyloxy, phenoxy and phenyl at the end of the truncated ω-chain.

Especially preferred compounds include a 13,14-dihydro-15-keto-PGcompound that has a single bond between positions 13 and 14; a15-keto-20-lower alkyl (especially ethyl) PG compound that has a loweralkyl, especially ethyl, at carbon atom of position 20; a 15-keto-PGFcompound that has hydroxy groups at positions 9 and position 11 of thefive membered ring.

A preferred prostaglandin compound used in the present invention isrepresented by the formula (I):

wherein L, M and N are hydrogen, hydroxy, halogen, lower alkyl,hydroxy(lower)alkyl, lower alkanoyloxy or oxo, wherein at least one of Land M is a group other than hydrogen, and the five-membered ring mayhave at least one double bond;

A is —CH₃, or —CH₂OH, —COCH₂OH, —COOH or a functional derivativethereof;

B is —CH₂—CH₂—, —CH═CH—, —C≡C—, —CH₂—CH₂—CH₂—, —CH═CH—CH₂—, —CH₂—CH═CH—,—C≡C—CH₂— or —CH₂—C≡C—;

Z is

wherein R₄ and R₅ are hydrogen, hydroxy, halogen, lower alkyl, loweralkoxy or hydroxy(lower)alkyl, wherein R₄ and R₅ are not hydroxy andlower alkoxy at the same time;

R₁ is a saturated or unsaturated bivalent lower or medium aliphatichydrocarbon residue, which is unsubstituted or substituted with halogen,alkyl, hydroxy, oxo, aryl or heterocyclic group, and at least one carbonatom in the aliphatic hydrocarbon is optionally substituted by oxygen,nitrogen or sulfur; and

Ra is a saturated or unsaturated lower or medium aliphatic hydrocarbonresidue, which is unsubstituted or substituted with halogen, oxo,hydroxy, lower alkoxy, lower alkanoyloxy, cyclo(lower)alkyl,cyclo(lower)alkyloxy, aryl, aryloxy, heterocyclic group orhetrocyclic-oxy group, and at least one carbon atom in the aliphatichydrocarbon is optionally substituted by oxygen, nitrogen or sulfur;lower alkoxy; lower alkanoyloxy; cyclo(lower)alkyl;cyclo(lower)alkyloxy; aryl; aryloxy; heterocyclic group;heterocyclic-oxy group.

A more preferred prostaglandin compound used in the present invention isrepresented by the formula (II):

wherein L and M are hydrogen, hydroxy, halogen, lower alkyl,hydroxy(lower)alkyl, lower alkanoyloxy or oxo, wherein at least one of Land M is a group other than hydrogen, and the five-membered ring mayhave one or more double bonds;

A is —CH₃, or —CH₂OH, —COCH₂OH, —COOH or a functional derivativethereof;

B is —CH₂—CH₂—, —CH═CH—, —C≡C—, —CH₂—CH₂—CH₂—, —CH═CH—CH₂—, —CH₂—CH═CH—,—C≡C—CH₂— or —CH₂—C≡C—;

Z is

wherein R₄ and R₅ are hydrogen, hydroxy, halogen, lower alkyl, loweralkoxy or hydroxy(lower)alkyl, wherein R₄ and R₅ are not hydroxy andlower alkoxy at the same time;

X₁ and X₂ are hydrogen, lower alkyl, or halogen;

R₁ is a saturated or unsaturated bivalent lower or medium aliphatichydrocarbon residue, which is unsubstituted or substituted with halogen,alkyl, hydroxy, oxo, aryl or heterocyclic group, and at least one carbonatom in the aliphatic hydrocarbon is optionally substituted by oxygen,nitrogen or sulfur;

R₂ is a single bond or lower alkylene, and at least one carbon atom inthe lower alkylene is optionally substituted by oxygen, nitrogen orsulfur; and

R₃ is lower alkyl, lower alkoxy, lower alkanoyloxy, cyclo(lower)alkyl,cyclo(lower)alkyloxy, aryl, aryloxy, heterocyclic group orheterocyclic-oxy group.

In the above formula, the term “unsaturated” in the definitions for R₁and Ra is intended to include at least one or more double bonds and/ortriple bonds that are isolatedly, separately or serially present betweencarbon atoms of the main and/or side chains. According to the usualnomenclature, an unsaturated bond between two serial positions isrepresented by denoting the lower number of the two positions, and anunsaturated bond between two distal positions is represented by denotingboth of the positions.

The term “lower or medium aliphatic hydrocarbon” refers to a straight orbranched chain hydrocarbon group having 1 to 14 carbon atoms (for a sidechain, 1 to 3 carbon atoms are preferable) and preferably 1 to 10,especially 1 to 8 carbon atoms.

The term “halogen atom” covers fluorine, chlorine, bromine and iodine.

The term “lower” throughout the specification is intended to include agroup having 1 to 6 carbon atoms unless otherwise specified.

The term “lower alkyl” refers to a straight or branched chain saturatedhydrocarbon group containing 1 to 6 carbon atoms and includes, forexample, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl,pentyl and hexyl.

The term “lower alkylene” refers to a straight or branched chainbivalent saturated hydrocarbon group containing 1 to 6 carbon atoms andincludes, for example, methylene, ethylene, propylene, isopropylene,butylene, isobutylene, t-butylene, pentylene and hexylene.

The term “lower alkoxy” refers to a group of lower alkyl-O—, whereinlower alkyl is as defined above.

The term “hydroxy(lower)alkyl” refers to a lower alkyl as defined abovewhich is substituted with at least one hydroxy group such ashydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl and1-methyl-1-hydroxyethyl.

The term “lower alkanoyloxy” refers to a group represented by theformula RCO—O—, wherein RCO— is an acyl group formed by oxidation of alower alkyl group as defined above, such as acetyl.

The term “cyclo(lower)alkyl” refers to a cyclic group formed bycyclization of a lower alkyl group as defined above but contains threeor more carbon atoms, and includes, for example, cyclopropyl,cyclobutyl, cyclopentyl and cyclohexyl.

The term “cyclo(lower)alkyloxy” refers to the group ofcyclo(lower)alkyl-O—, wherein cyclo(lower)alkyl is as defined above.

The term “aryl” may include unsubstituted or substituted aromatichydrocarbon rings (preferably monocyclic groups), for example, phenyl,tolyl, xylyl. Examples of the substituents are halogen atom andhalo(lower)alkyl, wherein halogen atom and lower alkyl are as definedabove.

The term “aryloxy” refers to a group represented by the formula ArO—,wherein Ar is aryl as defined above.

The term “heterocyclic group” may include mono- to tri-cyclic,preferably monocyclic heterocyclic group which is 5 to 14, preferably 5to 10 membered ring having optionally substituted carbon atom and 1 to4, preferably 1 to 3 of 1 or 2 type of hetero atoms selected fromnitrogen atom, oxygen atom and sulfur atom. Examples of the heterocyclicgroup include furyl, thienyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl,isothiazolyl, imidazolyl, pyrazolyl, furazanyl, pyranyl, pyridyl,pyridazinyl, pyrimidyl, pyrazinyl, 2-pyrrolinyl, pyrrolidinyl,2-imidazolinyl, imidazolidinyl, 2-pyrazolinyl, pyrazolidinyl,piperidino, piperazinyl, morpholino, indolyl, benzothienyl, quinolyl,isoquinolyl, purinyl, quinazolinyl, carbazolyl, acridinyl,phenanthridinyl, benzimidazolyl, benzimidazolinyl, benzothiazolyl,phenothiazinyl. Examples of the substituent in this case includehalogen, and halogen substituted lower alkyl group, wherein halogen atomand lower alkyl group are as described above.

The term “heterocyclic-oxy group” means a group represented by theformula HcO—, wherein Hc is a heterocyclic group as described above.

The term “functional derivative” of A includes salts, preferablypharmaceutically acceptable salts, ethers, esters and amides.

Suitable “pharmaceutically acceptable salts” include salts formed withnon-toxic bases conventionally used in pharmaceutical field, for examplea salt with an inorganic base such as an alkali metal salt (such assodium salt and potassium salt), an alkaline earth metal salt (such ascalcium salt and magnesium salt), an ammonium salt; or a salt with anorganic base, for example, an amine salt including such as methylaminesalt, dimethylamine salt, cyclohexylamine salt, benzylamine salt,piperidine salt, ethylenediamine salt, ethanolamine salt, diethanolaminesalt, triethanolamine salt, tris(hydroxymethylamino)ethane salt,monomethyl-monoethanolamine salt, procaine salt and caffeine salt), abasic amino acid salt (such as arginine salt and lysine salt),tetraalkyl ammonium salt and the like. These salts may be prepared by aconventional process, for example from the corresponding acid and baseor by salt interchange.

Examples of the ethers include alkyl ethers, for example, lower alkylethers such as methyl ether, ethyl ether, propyl ether, isopropyl ether,butyl ether, isobutyl ether, t-butyl ether, pentyl ether and1-cyclopropyl ethyl ether; and medium or higher alkyl ethers such asoctyl ether, diethylhexyl ether, lauryl ether and cetyl ether;unsaturated ethers such as oleyl ether and linolenyl ether; loweralkenyl ethers such as vinyl ether, allyl ether; lower alkynyl etherssuch as ethynyl ether and propynyl ether; hydroxy(lower)alkyl etherssuch as hydroxyethyl ether and hydroxyisopropyl ether; lower alkoxy(lower)alkyl ethers such as methoxymethyl ether and 1-methoxyethylether; optionally substituted aryl ethers such as phenyl ether, tosylether, t-butylphenyl ether, salicyl ether, 3,4-di-methoxyphenyl etherand benzamidophenyl ether; and aryl(lower)alkyl ethers such as benzylether, trityl ether and benzhydryl ether.

Examples of the esters include aliphatic esters, for example, loweralkyl esters such as methyl ester, ethyl ester, propyl ester, isopropylester, butyl ester, isobutyl ester, t-butyl ester, pentyl ester and1-cyclopropylethyl ester; lower alkenyl esters such as vinyl ester andallyl ester; lower alkynyl esters such as ethynyl ester and propynylester; hydroxy(lower)alkyl ester such as hydroxyethyl ester; loweralkoxy (lower) alkyl esters such as methoxymethyl ester and1-methoxyethyl ester; and optionally substituted aryl esters such as,for example, phenyl ester, tolyl ester, t-butylphenyl ester, salicylester, 3,4-di-methoxyphenyl ester and benzamidophenyl ester; andaryl(lower)alkyl ester such as benzyl ester, trityl ester and benzhydrylester.

The amide of A means a group represented by the formula —CONR′R″,wherein each of R′ and R″ is hydrogen, lower alkyl, aryl, alkyl- oraryl-sulfonyl, lower alkenyl and lower alkynyl, and include for examplelower alkyl amides such as methylamide, ethylamide, dimethylamide anddiethylamide; arylamides such as anilide and toluidide; and alkyl- oraryl-sulfonylamides such as methylsulfonylamide, ethylsulfonyl-amide andtolylsulfonylamide.

Preferred examples of L and M include hydrogen, hydroxy and oxo, andespecially, a compound wherein both of L and M are hydroxy which has a5-membered ring structure of, so called, PGF type, or a compound whereinL is hydroxy and M is oxo which has a 5-membered ring structure of, socalled, PGE type. PGF type is more preferable.

Preferred example of A is —COOH, its pharmaceutically acceptable salt,ester or amide thereof.

Preferred example of B is —CH₂—CH₂—, which provides a compound so called13,14-dihydro type PG.

Preferred examples of X₁ and X₂ comprise hydrogen and halogen andpreferably, both are hydrogen atom or at least one of them is a halogen.The compound wherein both of X₁ and X₂ are fluorine, which provides acompound so called 16,16-difluoro type PG, is also preferable.

Preferred R₁ is a hydrocarbon residue containing 1-10 carbon atoms,preferably 6-10 carbon atoms. Further, at least one carbon atom in thealiphatic hydrocarbon is optionally substituted by oxygen, nitrogen orsulfur.

Examples of R₁ include, for example, the following groups:

—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—,

—CH₂—CH═CH—CH₂—CH₂—CH₂—,

—CH₂—CH₂—CH₂—CH₂—CH═CH—,

—CH₂—C≡C—CH₂—CH₂—CH₂—,

—CH₂—CH₂—CH₂—CH₂—O—CH₂—,

—CH₂—CH═CH—CH₂—O—CH₂—,

—CH₂—C≡C—CH₂—O—CH₂—,

—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—,

—CH₂—CH═CH—CH₂—CH₂—CH₂—CH₂—,

—CH₂—CH₂—CH₂—CH₂—CH₂—CH═CH—,

—CH₂—C≡C—CH₂—CH₂—CH₂—CH₂—,

—CH₂—CH₂—CH₂—CH₂—CH₂—CH(CH₃)—CH₂—,

—CH₂—CH₂—CH₂—CH₂—CH(CH₃)—CH₂—,

—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—,

—CH₂—CH═CH—CH₂—CH₂—CH₂—CH₂—CH₂—,

—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—CH═CH—,

—CH₂—C≡C—CH₂—CH₂—CH₂—CH₂—CH₂—, and

—CH₂—CH₂—CH₂—CH₂—CH₂—CH₂—CH(CH₃)—CH₂—.

Preferred Ra is a hydrocarbon containing 1-10 carbon atoms, morepreferably, 1-8 carbon atoms. Ra may have one or two side chains havingone carbon atom.

The configuration of the ring and the α- and/or ω chains in the aboveformula (I) and (II) may be the same as or different from that of theprimary PGs. However, the present invention also includes a mixture of acompound having a primary type configuration and a compound of anon-primary type configuration.

The typical example of the present compounds are13,14-dihydro-15-keto-20-ethyl-PGF compound or13,14-dihydro-15-keto-17-phenyl-18,19,20-trinor-prostaglandin F compoundand its derivative or analogue, or13,14-dihydro-17-phenyl-18,19,20-trior-PGF_(2α) isopropyl ester,16-(3-trifluoromethyl phenoxy)-17,18,19,20-tetranor PGF_(2α) isopropylester or 17-phenyl-18,19,20-trinor-PGF_(2α) N-ethylamide.

In the present invention, the PG compound which is dihydro between 13and 14, and keto(═O) at 15 position may be in the keto-acetalequilibrium by formation of a hemiacetal between hydroxy at position 11and keto at position 15.

For example, it has been revealed that when both of X₁ and X₂ arehalogen atoms, especially, fluorine atoms, the compound contains atautomeric isomer, bicyclic compound.

If such tautomeric isomers as above are present, the proportion of bothtautomeric isomers varies, with the structure of the rest of themolecule or the kind of the substituent present. Sometimes one isomermay predominantly be present in comparison with the other. However, itis to be appreciated that the present invention includes both isomers.

Further, the 15-keto-PG compounds used in the invention include thebicyclic compound and analogs or derivatives thereof.

The bicyclic compound is represented by the formula (III)

wherein, A is —CH₃, or —CH₂OH, —COCH₂OH, —COOH or a functionalderivative thereof;

X₁′ and X₂′ are hydrogen, lower alkyl, or halogen;

X is

wherein R₄′ and R₅′ are hydrogen, hydroxy, halogen, lower alkyl, loweralkoxy or hydroxy(lower)alkyl, wherein R₄′ and R₅′ are not hydroxy andlower alkoxy at the same time.

R₁ is a saturated or unsaturated bivalent lower or medium aliphatichydrocarbon residue, which is unsubstituted or substituted with halogen,alkyl, hydroxy, oxo, aryl or heterocyclic group, and at least one carbonatom in the aliphatic hydrocarbon is optionally substituted by oxygen,nitrogen or sulfur; and

R₂′ is a saturated or unsaturated lower or medium aliphatic hydrocarbonresidue, which is unsubstituted or substituted with halogen, oxo,hydroxy, lower alkoxy, lower alkanoyloxy, cyclo(lower)alkyl,cyclo(lower)alkyloxy, aryl, aryloxy, heterocyclic group orhetrocyclic-oxy group; lower alkoxy; lower alkanoyloxy;cyclo(lower)alkyl; cyclo(lower)alkyloxy; aryl; aryloxy; heterocyclicgroup; heterocyclic-oxy group.

R₃′ is hydrogen, lower alkyl, cyclo(lower)alkyl, aryl or heterocyclicgroup.

Furthermore, while the compounds used in the invention may berepresented by a formula or name based on keto-type regardless of thepresence or absence of the isomers, it is to be noted that suchstructure or name does not intend to exclude the acetal type compound.

In the present invention, any of isomers such as the individualtautomeric isomers, the mixture thereof, Or optical isomers, the mixturethereof, a racemic mixture, and other steric isomers may be used in thesame purpose.

Some of the compounds used in the present invention may be prepared bythe method disclosed in U.S. Pat. Nos. 5,073,569, 5,166,174, 5,221,763,5,212,324, 5,739,161 and 6,242,485 these cited references are hereinincorporated by reference.

The PG compounds described as above are useful as agent for treatingvarious symptoms in the ophthalmic area. For example, it is useful fortreating glaucoma and/or ocular hypertension, cataract and optic nervedisorders and for increasing the choroidal blood flow.

The term “ophthalmic solution” used herein refers any form of liquidcomposition suitable for topical eye administration and the liquidcomposition may be in the form of solution, emulsion or suspension.

The term “treatment” or “treating” used herein refers to any means ofcontrol of a condition including prevention, cure, relief of thecondition, and arrestation or relief of development of the condition.

In the ophthalmic solution of the present invention, the PG compound,the active ingredient, may be any of the above described compounds.

The amount of the PG compound in the ophthalmic, solution is not limitedas long as it is sufficient to provide the expected therapeutic effects.In general, the amount of the PG compound in the solution may be fromabout 0.00001 to about 10 w/v %, preferably, about 0.0001 to about 5 w/v%, more preferably about 0.001 to about 1 w/v % of the solution.

In this specification and claims, “viscosity-increasing compound”represents a polymer compound which can increase viscosity of an aqueousmedium when it is dissolved or dispersed in the medium. The combinationof the viscosity-increasing compound and PG compound is excellent instability and provides long-lasting and increased effects.Viscosity-increasing compound may preferably be selected from the groupconsisting of acrylate polymers, polyols, cellulose polymers,polysaccharides and polyl-lactams. Examples of the viscosity-increasingcompounds include acrylate polymers, or also called as carboxyvinylpolymers, such as carbomer, for example CARBOPOL™ 941, 934, 940, 971,974, 980 and 981, and polycarbophil, for example NOVEON™ AA-1, CA-1 andCA-2; polyols such as polyvinyl alcohols, glycerin, polyethyleneglycols;cellulose polymers such as methylcellulose, methylethylcellulose,hydroxypropylmethylcellulose, hydroxyethylcellulose, andcarboxymethylcellulose; polysaccharides such as carrageenan, gellan gum,xanthan gum, dextran and locust bean gum; poly-lactams such as polyvinylpyrrolidone.

Based on the necessity or purpose of the treatment, theviscosity-increasing compound may optionally be a combination of two ormore above-described compounds. Further, if it is required, the otherviscosity-increasing compounds such as gelatins may be admixed with theabove described viscosity-increasing compounds of the present invention.

The amount of the viscosity-increasing compound in the presentophthalmic solution may vary depending on the amount of the PG compound,or the kind or the molecular weight of the viscosity-increasing compoundemployed. Generally, the amount of about 0.001-30 w/v %, preferablyabout 0.01-10 w/v % of the whole solution is enough to provide theexpected effect.

The ophthalmic solution of the present invention may be manufactured bya conventional manner, for example, by adding a PG compound and aviscosity-increasing compound to an aqueous solution such asphysiological saline or buffering solution, etc., and dissolving ormixing them or by combining powder composition with the aqueous solutionas above or water before use. Further, in order to improve thesolubility of the PG compound to water, esters of polyoxyethylenesorbitane mono higher fatty acid such as polysorbate 80, may be added tothe purified water. Alternatively, by mixing a PG compound with an esterof polyoxyethylene sorbitane mono higher fatty acid and then adding themixture to purified water. The concentration of the esters ofpolyoxyethylene sorbitane mono higher fatty acid may vary depending onthe amount of the PG, and in general, may be 0.01-10 w/w %, preferably,0.05-5 w/w % of whole solution.

In addition, the ophthalmic solution of the present invention maycontain other active ingredients in so far as it does not act adverse tothe purpose of the present invention.

The ophthalmic solution of the present invention may further containadditives which have been employed in conventional ophthalmic solutions.For example, buffers or isotonic agents such as salts like phosphates(e.g. sodium monohydrogen phosphate and sodium dihydrogen phosphate),borates, sodium chloride or mannitol; dissolving agent such aspolysorbate 80 or polyoxyethylene hydrogenated caster oil such aspolyethylene hydrogenated caster oil 60; preservatives such asbenzalkonium chloride, benzethonium chloride, chloro butanol or paraben.

The present composition may be formulated as a sterile unit dose typeproduct comprising no preservatives.

The ophthalmic solution of the invention is useful for treatingglaucoma, cataract or optic nerve disorders, or for lowering theintraocular pressure or for increasing the choroidal blood flow. Theophthalmic solution of the present invention can provide enoughtherapeutic effect, since it is excellent in stability and the durationand potency of the effect of the PG compound is elongated. Further, theophthalmic solution of the present invention can provide an improvedcompliance for the patients due to the reduced administration frequency(e.g. once a day) of the PG compound, which may be expected the reducedside effect such as corneal disorder. Accordingly, the ophthalmicsolution of the present invention may be useful for treatment of avarious symptoms in the ophthalmic area.

The present invention will be explained in more detail by means of thefollowing examples, which are illustrated by way of example only andnever intended to limit the scope of the present invention.

Test Example

Test ophthalmic solutions comprising 0.12 w/v % of13,14-dihydro-15-keto-20-ethyl-PGF₂α isopropyl ester (test compound 1)were prepared.

Test solution 1: Rescula™ ophthalmic solution (0.12%)(R-tech UENO, Ltd.Tokyo, Japan)Test solution 2: prepared by adding 1 w/v % methyl cellulose 400 cP tothe test solution 1.Test solution 3: prepared by replacing sodium chloride contained in thetest solution 1 as isotonic agent with 3.5 w/v % mannitol and adding 0.3w/v % gellan gum to the solution.

Normal white rabbits were used. Test solution (30 μL/eye) wasadministered to one eye and vehicle of the test solution, i.e. the samesolution as the test solution except for comprising test compound 1, wasadministrated to the other eye of the rabbit (30 μL/eye). Theintraocular pressure (IOP) of the animals were measured with anapplanation tonometer immediately before and 2, 4 and 6 hours after theadministration. Change of IOP (ΔIOP) at each measurement time from thatmeasured just before the administration (time 0) was calculated.

Results are shown in tables 1, 2 and 3. Test solution 2 and 3, whichcomprising certain viscosity-increasing compound, exhibitedsignificantly longer lasting and increased IOP lowering effect than testsolution 1 containing no viscosity increasing compound.

TABLE 1 Change of IOP in normal white rabbits after administration oftest solution 1 change of IOP (mean ± SE, mmHg) time afteradministration (hr) Test Solution n 0 2 4 6 Vehicle for test 8 0.0 ± 0.0  2.8 ± 0.7    1.4 ± 0.9    1.1 ± 0.6 solution 1 Test Solution 1 8 0.0 ±0.0 −2.9 ± 0.7** −2.0 ± 1.0* −0.1 ± 1.4 **P < 0.01, *p < 0.05 Comparedwith the other eye received the vehicle (paired Student's t -test)

TABLE 2 Change of IOP in normal white rabbits after administration oftest solution 2 change of IOP (mean ± SE, mmHg) time afteradministration (hr) Test Solution n 0 2 4 6 Vehicle for test 8 0.0 ± 0.0  2.3 ± 0.5    2.0 ± 0.7    2.0 ± 0.8  solution 2 Test Solution 2 8 0.0± 0.0 −3.9 ± 0.7** −3.3 ± 1.3** −1.0 ± l.1* **P < 0.01, *p < 0.05Compared with the other eye received the vehicle (paired Student'st-test)

TABLE 3 Change of IOP in normal white rabbits after administration oftest solution 3 change of IOP (mean ± SE, mmHg) time afteradministration (hr) Test Solution n 0 2 4 6 Vehicle for test 8 0.0 ± 0.0  1.1 ± 1.0    0.1 ± 0.8    1.3 ± 0.8  solution 3 Test Solution 3 8 0.0± 0.0 −3.4 ± 0.5** −3.6 ± 0.5** −2.0 ± 1.0** **P < 0.01, *p < 0.05Compared with the other eye received the vehicle (paired Student's t-test)

Formulation Example 1

Twelve (12) mg of isopropyl unoprostone, 50 mg of CARBOPOL™ 940 and 90mg of polysorbate 80 were admixed with 50 ml of purified water, morepurified water was added to make the total volume 100 ml, and dissolvedthe mixture to provide Ophthalmic solution 1.

Formulation Example 2

Ophthalmic solution 2 was prepared by the same manner as Example 1except for 200 mg of polyvinyl alcohol was added in place of CARBOPOL940.

Formulation Example 3

Ophthalmic solution 3 was prepared by the same manner as Example 1except for 150 mg of glycerin was added in place of CARBOPOL 940.

Formulation Example 4

Ophthalmic solution 4 was prepared by the same manner as Example 1except for 20 mg of hydroxymethyl cellulose was added in place ofCARBOPOL 940.

Formulation Example 5

Ophthalmic solution 5 was prepared by the same manner as Example 1except for 100 mg of polyvinyl pyrrolidone was added in place ofCARBOPOL 940.

What is claimed is:
 1. A method for improving the duration and/orpotency of the effect of an ophthalmic solution comprising13,14-dihydro-15-keto-20-ethyl-prostaglandin F2α isopropyl ester whenadministered to the eyes of a subject, comprising: adding methylcellulose in an amount of about 0.01-10 w/v % to the ophthalmicsolution.
 2. The method of claim 1, wherein the ophthalmic solutioncomprises 13,14-dihydro-15-keto-20-ethyl-prostaglandin F2α isopropylester in an amount of about 0.001-1 w/v %.
 3. The method of claim 2,wherein the ophthalmic solution comprises13,14-dihydro-15-keto-20-ethyl-prostaglandin F2α isopropyl ester in anamount of about 0.12 w/v %.
 4. The method of claim 1, wherein the methodimproves the duration of the intraocular pressure lowering effect of theophthalmic solution to longer than 4 hours.
 5. The method of claim 1,wherein the ophthalmic solution is administered to a patient in needthereof only once a day.
 6. The method of claim 1, further comprising adissolving agent.